<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>统计 object 中有多少个 key</title>
</head>
<body>
    <script>
        var num={
            p1:'key',
            p2:'key',
            p3:'key',
            p4:'aaa'

        }
        for(var kay in num){
            console.log(num[kay].length);
        }

    </script>
</body>
</html>